A virtual machine snapshot means copying and storing a status, which is at a specific moment, of a virtual machine in order to restore the virtual machine according to the virtual machine snapshot when a system encounters a problem, or restore the virtual machine to a running state at the moment according to the virtual machine snapshot after the virtual machine starts. An online snapshot means storing a working status of a current virtual machine to a specified file without interrupting normal running of the current virtual machine.
The virtual machine snapshot includes a device status and memory data of the virtual machine. At present, a kernel-based virtual machine (KVM) does not have an online memory snapshot function. When a snapshot of the KVM is being obtained, the virtual machine needs to be suspended first, and then content in a virtual memory of the virtual machine and the device status are live migrated to a snapshot file. However, live migration from the memory of the virtual machine to the snapshot file takes a relatively long time, and therefore the virtual machine is suspended for a relatively long time, greatly affecting a service of the virtual machine.